Surgical robotic systems

ABSTRACT

An instrument drive unit for use in a robotic surgical system includes a carriage configured to be coupled to a robotic arm, a hub rotationally coupled to the carriage and configured to be non-rotatably coupled to an electromechanical surgical instrument, a plurality of electric motors disposed within the carriage, a plurality of drive shafts rotationally supported in the hub, and a plurality of drive gears. Each electric motor includes a stator and a rotor disposed within the stator. Each drive gear is fixed to a corresponding drive shaft and is configured for interfacing with a corresponding driven member of the electromechanical surgical instrument. Each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor to actuate a function of the electromechanical surgical instrument.

BACKGROUND

Surgical robotic systems have been used in minimally invasive medical procedures. Some surgical robotic systems included a console supporting a surgical robotic arm and a surgical instrument having at least one end effector (e.g., forceps or a grasping tool) mounted to the robotic arm. The robotic arm provided mechanical power to the surgical instrument for its operation and movement.

Manually-operated surgical instruments often included a handle assembly for actuating the functions of the surgical instrument. However, when using a robotic surgical system, no handle assembly was typically present to actuate the functions of the end effector. Accordingly, to use each unique surgical instrument with a robotic surgical system, an instrument drive unit was used to interface with the selected surgical instrument to drive operations of the surgical instrument.

The instrument drive unit was typically coupled to the robotic arm via a slide. The slide allowed the instrument drive unit and the attached surgical instrument to move along an axis of the slide, providing a means for adjusting the axial position of the end effector of the surgical instrument.

SUMMARY

In accordance with an aspect of the present disclosure, an instrument drive unit for use in a robotic surgical system is provided and includes a carriage configured to be coupled to a robotic arm, a hub rotationally coupled to the carriage and configured to be non-rotatably coupled to an electromechanical surgical instrument, a plurality of electric motors disposed within the carriage, a plurality of drive shafts rotationally supported in the hub, and a plurality of drive gears. Each electric motor includes a stator and a rotor disposed within the stator. Each drive gear is fixed to a corresponding drive shaft and configured for interfacing with a corresponding driven member of the electromechanical surgical instrument. Each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor to actuate a function of the electromechanical surgical instrument.

In aspects, each stator may be fixed relative to the carriage, and each rotor may be rotatable relative to and within a corresponding stator.

In some aspects, the electrical motors may be vertically stacked within the carriage.

In other aspects, the instrument drive unit may further include a drive motor including a stator fixed within the carriage, and a rotor disposed within the stator of the drive motor and non-rotatably coupled to the hub. The rotor of the drive motor may be configured to rotate the hub about a central longitudinal axis defined by the hub.

In further aspects, the instrument drive unit may further include a sleeve rotatably coupled to a distal end portion of the carriage and non-rotatably coupled to the hub. The sleeve may be configured to non-rotatably receive the electromechanical surgical instrument, such that a rotation of the hub results in a rotation of the electromechanical surgical instrument.

In aspects, the instrument drive unit may further include a plurality of ring gears. Each ring gear may be fixed to a corresponding rotor and operably coupled to a corresponding drive gear.

In some aspects, each ring gear may be concentrically disposed within a corresponding rotor, such that rotation of the rotor results in a rotation of the corresponding ring gear.

In other aspects, the ring gears may be vertically stacked within the hub.

In further aspects, a first electric motor, a first ring gear, and a first drive gear may be operably coupled to one another and aligned along a first horizontal plane, and a second electric motor, a second ring gear, and a second drive gear may be operably coupled to one another and aligned along a second horizontal plane, vertically displaced from the first horizontal plane.

In another aspect, the ring gears may be independently rotatable relative to one another.

In aspects, a first ring gear may have gear teeth on an inner periphery thereof. The gear teeth may interface with a corresponding drive gear, and an outer periphery of the first ring gear may be attached to an inner periphery of a corresponding rotor.

In some aspects, the drive shafts may be circumferentially spaced from one another.

In other aspects, the drive gears may be vertically offset from one another.

In other aspects, each drive shaft may have a distal end portion configured for interfacing with a corresponding driven member of the electromechanical surgical instrument.

In another aspect of the present disclosure, an instrument drive unit for use in a robotic surgical system is provided and includes a carriage configured to be coupled to a robotic arm, a plurality of electric motors supported in the carriage, and a plurality of drive shafts circumferentially spaced from one another. Each electric motor includes a stator and a rotor disposed within the stator. The drive shafts are configured for interfacing with a corresponding driven member of an electromechanical surgical instrument. Each drive shaft has a drive gear fixed thereabout, and each drive gear is disposed at a discrete vertical location relative to one another. Each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor to actuate a function of the electromechanical surgical instrument.

In aspects, the instrument drive unit may further include a plurality of vertically stacked ring gears. Each ring gear may be fixed to a corresponding rotor and operably coupled to a corresponding drive gear, such that each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor to actuate a function of the electromechanical surgical instrument.

In some aspects, the instrument drive unit may further include a hub rotationally coupled to the carriage, and a drive motor operably coupled to the hub. The hub may be configured to be non-rotatably coupled to the electromechanical surgical instrument. The drive shafts may be rotationally supported in the hub. The drive motor may be configured to rotate the hub about a central longitudinal axis defined by the hub.

Further details and aspects of exemplary embodiments of the present disclosure are described in more detail below with reference to the appended figures.

As used herein, the terms parallel and perpendicular are understood to include relative configurations that are substantially parallel and substantially perpendicular up to about + or −10 degrees from true parallel and true perpendicular.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described herein with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a surgical robotic system including an instrument drive unit coupled to a slide in accordance with the present disclosure;

FIG. 2 is a perspective view of the instrument drive unit of the surgical robotic system of FIG. 1 with an outer carriage removed;

FIG. 3 is a longitudinal cross-sectional view of the instrument drive unit of FIG. 2 with the outer carriage removed;

FIG. 4 is another longitudinal cross-sectional view of the instrument drive unit of FIG. 2 with the outer carriage shown; and

FIG. 5 is a side cross-sectional view of the instrument drive unit of FIG. 2.

DETAILED DESCRIPTION

Embodiments of the presently disclosed surgical robotic system and instrument drive units thereof are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “distal” refers to that portion of the surgical robotic system or component thereof that is closest to the patient, while the term “proximal” refers to that portion of the surgical robotic system or component thereof further from the patient. As used herein, the term “vertical” refers to a direction defined along a longitudinal axis of a portion of the surgical robotic system, while the term “horizontal” refers to a direction defined along a transverse axis of a portion of the surgical robotic system.

As will be described in detail below, provided is an instrument drive unit of a surgical robotic system configured to allow for a bottom-loading of a surgical instrument. The instrument drive unit has a plurality of drive shafts each configured to be coupled to a corresponding driven member of the surgical instrument for carrying out a discrete function of the surgical instrument. The drive shafts of the instrument drive unit are operably coupled to a discrete electric motor of the instrument drive unit via a discrete transmission assembly. The configuration of the transmission assemblies allows for a reduction in the overall height of the instrument drive unit (e.g., the instrument drive unit is more compact). For example, gears of the transmission assemblies are vertically and horizontally offset from the gears of the other transmission assemblies. The instrument drive unit may also include a rotatable hub that rotationally supports the drive shafts. The hub is configured to be rotated via a separate drive motor to enable rotation of the attached surgical instrument about its longitudinal axis. Other features and benefits of the disclosed instrument drive units are further detailed below.

Referring initially to FIG. 1, a surgical system, such as, for example, a surgical robotic system 1, generally includes a plurality of surgical robotic arms 2, 3; an elongated slide 13 coupled to an end of each of the robotic arms 2, 3; an instrument drive unit 20 and an electromechanical instrument 10 removably attached to the slide 13 and configured to move along the slide 13; a control device 4; and an operating console 5 coupled with control device 4. The operating console 5 includes a display device 6, which is set up in particular to display three-dimensional images; and manual input devices 7, 8, by means of which a person (not shown), for example a surgeon, is able to telemanipulate robotic arms 2, 3 in a first operating mode, as known in principle to a person skilled in the art.

Each of the robotic arms 2, 3 may be composed of a plurality of members, which are connected through joints. Robotic arms 2, 3 may be driven by electric drives (not shown) that are connected to control device 4. Control device 4 (e.g., a computer) is set up to activate the drives, in particular by means of a computer program, in such a way that robotic arms 2, 3, the attached instrument drive units 20, and thus electromechanical instrument 10 execute a desired movement according to a movement defined by means of manual input devices 7, 8. Control device 4 may also be set up in such a way that it regulates the movement of the instrument drive unit 20 along the slide 13, movement of the robotic arms 2, 3, and/or movement of the drives.

Surgical robotic system 1 is configured for use on a patient “P” lying on a surgical table “ST” to be treated in a minimally invasive manner by means of a surgical instrument, e.g., electromechanical instrument 10. Surgical robotic system 1 may also include more than two robotic arms 2, 3, the additional robotic arms likewise being connected to control device 4 and being telemanipulatable by means of operating console 5. A surgical instrument, for example, an electromechanical surgical instrument 10 (including an electromechanical end effector), may also be attached to the additional robotic arm.

Control device 4 may control a plurality of motors, e.g., motors (Motor 1 . . . n), with each motor configured to drive movement of robotic arms 2, 3 in a plurality of directions. Further, control device 4 may control a plurality of electric motors 22 (FIGS. 2-5) of the instrument drive unit 20 to drive various operations of the surgical instrument 10. The instrument drive unit 20 transfers power and actuation forces from its motors to driven members (not shown) of the electromechanical instrument 10 to ultimately drive movement of components of the end effector of the electromechanical instrument 10, for example, a movement of a knife blade (not shown) and/or a closing and opening of jaw members of the end effector.

For a detailed description of the construction and operation of a robotic surgical system, reference may be made to U.S. Pat. No. 8,828,023, entitled “Medical Workstation,” the entire contents of which are incorporated by reference herein.

With reference to FIGS. 2-5, the instrument drive unit 20 will now be described in detail. The instrument drive unit 20 includes a carriage 26 (FIG. 4) and a coupling or sleeve 28 rotatably coupled to a distal end portion 26 b of the carriage 26 for connecting a surgical instrument 10 (FIG. 1) to the instrument drive unit 20. The carriage 26 of the instrument drive unit 20 is configured to be slidably coupled to a linear track (not shown) defined longitudinally along the slide 13 (FIG. 1). A proximal end portion 26 a of the carriage 26 houses a plurality of electric motors 22 a, 22 b, 22 c, 22 d, 22 d, 22 e (collectively referred herein as “22”) for carrying out various functions of an attached surgical instrument 10.

The carriage 26 defines a longitudinally-extending channel 30 therethrough dimensioned for receipt of a hub 46 of the instrument drive unit 20. The distal end portion 26 b has an annular ledge 32 (FIG. 4) that extends radially inward from an inner peripheral surface of the carriage 26. The annular ledge 32 is configured to support internal components of the instrument drive unit 20. In embodiments, the distal end portion 26 b of the carriage 26 may have a slip ring 33 received therein for transferring electrical signals or power between fixed structures (e.g., the electric motors 22) and rotating structures (e.g., the electromechanical surgical instrument 10). The electrical signals transferred by the slip ring 33 may be feedback signals from the electromechanical surgical instrument 10 relating to the status and location of the surgical instrument 10 and/or the status and location of adjacent tissue structures. For example, the feedback may include the temperature of the surgical instrument 10, forces experienced by the surgical instrument 10, and/or the position of certain structures of the surgical instrument 10 relative to one another or relative to the adjacent tissue structures.

The coupling or sleeve 28 of the instrument drive unit 20 is rotatably coupled to the distal end portion 26 b of the carriage 26. The sleeve 28 has a proximal end portion 28 a received within the channel 30 of the carriage 26 and fixed to the hub 46, such that the sleeve 28 rotates with the hub 46. The sleeve 28 has a plurality of annular members 29 (FIG. 4) fixed therein having a respective drive shaft 66 extending therethrough. Rotation of the hub 46 causes the drive shafts 66 to rotate therewith, which, in turn, drives a rotation of the sleeve 28, as will be described. The sleeve 28 has a distal end portion 28 b configured to non-rotationally fix the main body portion of the surgical instrument 10 therein. The sleeve 28 may have a pair of latch members 31 a, 31 b configured to releasably retain the main body portion of the electromechanical surgical instrument 10. Accordingly, when the surgical instrument 10 is coupled to the instrument drive unit 20, a rotation of the sleeve 28 results in a rotation of the attached surgical instrument 28.

The electric motors 22 of the instrument drive unit 20 are concealed within the carriage 26. The electric motors 22 are vertically stacked on one another and are independently actuatable via the control device 4 (FIG. 1). One of the electric motors, such as, for example, the fifth electric motor 22 e, is configured to effectuate a rotation of the surgical instrument 10 when the surgical instrument 10 is coupled to the instrument drive unit 20, and the remaining electric motors 22 a, 22 b, 22 c, 22 d are configured to actuate functions of the surgical instrument 10, as will be described. The electric motors 22 are integrated AC motors. In embodiments, the electric motors 22 may be any suitable type of electric motor such as an AC brushless motor, a DC brushed motor, a DC brushless motor, a direct drive motor, a servo motor, a stepper motor, or the like. It is contemplated, and within the scope of the present disclosure, that electric motors 22 are in the form of hollow core motors, or the like. Other types of motors are also contemplated.

While the instrument drive unit 20 is illustrated as having five electric motors, it is contemplated that the instrument drive unit 20 may have more or less than five electric motors.

The electric motors 22 each have a stator 40 a, 40 b, 40 c, 40 d, 40 e (collectively referred to herein as “40”) fixed within the carriage, and a rotor 42 a, 42 b, 42 c, 42 d, 42 d (collectively referred to herein as “42”) rotationally disposed within a corresponding stator 40. Each of the stators 40 may be annularly shaped and stacked on top of one another to form a hollow cylinder 43, as best shown in FIG. 2. The stators 40 are electrically isolated from one another by having an insulative material 45 interposed between adjacent, vertically stacked stators 40. The stators 40 may be configured to receive an electric current from a power source (not explicitly shown) to produce a rotating magnetic field that drives a rotation of the rotors 42.

Each of the rotors 42 may be configured as a permanent magnetic, an electromagnet, or any other suitable conductor. The rotors 42 are vertically stacked within the hollow cylinder 43 formed by the stators 40 and are independently rotatable relative to one another about a central longitudinal axis “X” defined by the hollow cylinder 43. The rotors 42 may be rotationally supported on the insulative material 45. It is contemplated that a bearing 51 may be interposed between adjacent, vertically stacked rotors 42 to facilitate independent rotation of the rotors 42.

The hub 46 of the instrument drive unit 20 is supported in the hollow cylinder 43 formed by the stators 40. The hub 46 is configured to rotate relative to and within the hollow cylinder 43. The hub 46 has a pair of proximal and distal plates 58 a, 58 b disposed adjacent respective proximal and distal ends thereof. The plates 58 a, 58 b axially support the hub 46 in the carriage 26. The hub 46 has a plurality of support struts 47 extending vertically between the plates 58 a, 58 b, thereby connecting the plates 58 a, 58 b and providing integrity to the hub 46. The hub 46 further includes a ring member 49 extending proximally from the proximal plate 58 a. The ring member 49 of the hub 46 has the rotor 42 e of the fifth electric motor 22 e disposed thereabout and fixed thereto. As such, a rotation of the rotor 42 e of the fifth electric motor 22 e drives a rotation of the hub 46 relative to the carriage 26 about the central longitudinal axis “X” defined by the hollow cylinder 43.

With continued reference to FIGS. 2-5, the instrument drive unit 20 further includes a plurality of transmission assemblies 60 a, 60 b, 60 c, 60 d (collectively referred to herein as “60”) that function independently from one another to transfer torque from a corresponding electric motor 22 to a corresponding driven member of the attached surgical instrument 10. Each transmission assembly 60 a, 60 b, 60 c, 60 d may include a ring gear 62 a, 62 b, 62 c, 62 d (collectively referred to herein as “62”), a drive gear 64 a, 64 b, 64 c, 64 d (collectively referred to herein as “64”), and a drive shaft 66 a, 66 b, 66 c, 66 d (collectively referred to herein as “66”) operably coupled to one another.

Components of the transmission assemblies 60 are vertically offset from one another along the central longitudinal axis “X” defined by the hollow cylinder 43, and certain components of each transmission assembly 60 are aligned along a horizontal plane. For example, the first ring gear 62 a and the first drive gear 64 a of the first transmission assembly 60 a (e.g., the distal-most transmission assembly) are operably coupled to one another and substantially aligned along a first horizontal plane “P1,” and the second ring gear 62 b and the second drive gear 64 b of the second transmission assembly 60 b are operably coupled to one another and substantially aligned along a second horizontal plane “P2,” which is vertically displaced (e.g., disposed distally) from the first horizontal plane “P1” along the longitudinal axis “X.” The remaining transmission assemblies 60 c and 60 d are also disposed in a discrete horizontal plane. While only four transmission assemblies are shown, it is contemplated that the instrument drive unit 20 may have more or less than four transmission assemblies.

The ring gears 62 of the transmission assemblies 60 are vertically stacked within the hollow cylinder 43. In particular, the ring gears 62 are coaxial along the central longitudinal axis “X” defined by the hollow cylinder 43. The ring gears 62 are disposed about the support struts 47 of the hub 46 and are interposed between the proximal and distal plates 58 a, 58 b of the hub 46.

As best shown in FIG. 5, each of the ring gears 62 has an outer periphery 70 adhered to an inner periphery 73 of a respective rotor 42, such that each ring gear 62 and rotor 42 pair (e.g., ring gear 62 d and rotor 42 d) rotate together relative to the corresponding stator 40. Each ring gear 62 has gear teeth 68 extending from an inner periphery 72 thereof. The gear teeth 68 on the inner periphery 72 of each of the ring gears 62 interfaces with a corresponding drive gear 64, as will be described. In embodiments, each of the rings gears 62 may be constructed as a rotor 42 rather than being integrally connected with a rotor 42.

With reference to FIGS. 3-5, the drive shafts 66 a, 66 b, 66 c, 66 d of the transmission assemblies 60 a, 60 b, 60 c, 60 d extend longitudinally through the hub 46 and distally therefrom. In particular, each of the drive shafts 66 has a proximal end portion 67 a rotatably coupled to the proximal plate 58 a of the hub 46, an intermediate portion 67 c extending between the proximal and distal plates 58 a, 58 b of the hub 46, and a distal end portion 67 b extending distally from the distal plate 58 b of the hub 46. The drive shafts 66 are circumferentially spaced from one another about the central longitudinal axis “X” of the hollow cylinder 43. The drive shafts 66 are free to rotate about their respective longitudinal axes in relation to the hub 46.

The distal end portion 67 b of each of the drive shafts 66 is configured to operably couple to a driven member (not explicitly shown) of the surgical instrument 10. For example, the distal end portion 67 b of each of the drive shafts 66 may have a coupler (e.g., a gear) for coupling with a corresponding coupler of a driven member of the surgical instrument 10. Accordingly, upon bottom-loading of the electromechanical instrument 10 into the instrument drive unit 20, the distal end portions 67 b of the drive shafts 66 of the instrument drive unit 20 operably couple to the gears/couplers in a distal end of the main body portion (not shown) of the electromechanical instrument 10, such that a rotation of each drive shaft 66 rotates a correspondingly coupled driven member of the surgical instrument 10 to effectuate a discrete function of the surgical instrument (e.g., opening/closing of the end effector, articulation of the end effector, etc.)

The drive shafts 66 each have a drive gear 64 such as, for example, a spur gear, rotationally fixed thereabout. Each of the drive gears 64 are positioned at a discrete vertical location on their respective drive shaft 66, such that the drive gears 64 are vertically offset a selected distance from one another. Since the drive gears 64, in addition to being vertically offset, are also circumferentially spaced from one another, the drive gears 64 are offset from one another in all three dimensions. As mentioned above, the drive gears 64 each interface or intermesh with the gear teeth 68 on the inner periphery 72 of a corresponding ring gear 62 and receive torque therefrom originating from the respective rotor 42.

In operation, the electromechanical instrument 10 is coupled to the instrument drive unit 20 by passing the main body portion of the electromechanical instrument 10 through the sleeve 28 of the instrument drive unit 20 in a proximal direction. The latch members 31 a, 31 b of the sleeve 28 may engage opposing lateral sides of the main body portion of the surgical instrument 10 (FIG. 1) to selectively retain the surgical instrument 10 within the sleeve 28. With the main body portion of the electromechanical instrument 10 attached to the sleeve 28 of the instrument drive unit 28, the distal end portion 67 b of each of the drive shafts 66 interfaces with corresponding gears/couplers (not shown) in the proximal end of the main body portion of the electromechanical instrument 10.

With the electromechanical instrument 10 coupled to the instrument drive unit 20, to actuate a particular function of the surgical instrument 10, such as, for example, an opening or closing of an end effector of the surgical instrument 10, one of the electric motors 22 of the instrument drive unit 20, such as the first electric motor 22 a, is activated via the control device 4 (FIG. 1). An activation of the first electric motor 22 a includes supplying an electric current to the stator 40 a thereof, which drives a rotation of the rotor 42 a thereof. It is contemplated that the control device 4 or a processor (not shown) of the electric motor 22 a generates a rotating magnetic field about the stator 40 a to drive the rotation of the rotor 42 a. Rotation of the rotor 42 a actuates the first transmission assembly 60 a to transfer torque from the rotor 42 a to a first driven member of the electromechanical instrument 10.

An actuation of the first transmission assembly 60 a includes a rotation of the first ring gear 62 a of the first transmission assembly 60 a with the rotor 42 a, which, in turn, rotates the first drive gear 64 a of the first transmission assembly 60 a. Since the first drive gear 64 a is rotationally fixed about the first drive shaft 66 a, and the distal end portion 67 b of the first drive shaft 66 a is operably coupled to the proximal end of the first driven member of the surgical instrument 10 (FIG. 1), a rotation of the first drive gear 64 a causes the first drive shaft 66 a to rotate, thereby rotating the first driven member of the electromechanical instrument 10 to actuate an associated function of the surgical instrument 10.

It is contemplated that the fifth electric motor 22 e may be configured to resist rotation of the rotor 42 e thereof during actuation of any of the transmission assemblies 60 a, 60 b, 60 c, 60 d so that actuation of one of the transmission assemblies 60 a, 60 b, 60 c, 60 d does not inadvertently result in a rotation of the hub 46.

To rotate the electromechanical instrument 10 about its longitudinal axis, the fifth electric motor 22 e of the instrument drive unit 20 is activated by the control device 4 (FIG. 1). An activation of the fifth electric motor 22 e includes supplying an electric current to the stator 40 e thereof, which drives a rotation of the rotor 42 e thereof. Rotation of the rotor 42 e rotates the hub 46 about the central longitudinal axis “X” since the rotor 42 e is fixed to the ring member 49 of the hub 46. Due to the drive shafts 66 extending through the distal plate 58 b of the hub 46 and the annular members 29 (FIG. 4) of the sleeve 28, the sleeve 28 rotates with the hub 46. Given that the electromechanical instrument 10 is non-rotationally supported in the sleeve 28, the electromechanical instrument 10 rotates with the sleeve 28 relative to the carriage 26 to change a rotational orientation of the electromechanical instrument 10.

The electric motors 22 a, 22 b, 22 c, 22 d may be configured to synchronously rotate the rotors 40 a, 40 b, 40 c, 40 d, and in turn the drive gears 64 a, 64 b, 64 c, 64 d, with the rotation of the hub 46. This would prevent rotation of the drive shafts 66 a, 66 b, 66 c, 66 d about their respective longitudinal axes during rotation of the hub 46, which may otherwise occur if the drive gears 64 a, 64 b, 64 c, 64 d were held stationary during rotation of the hub 46. Conversely, the fifth motor 22 e may be actuated during an actuation of one of the electric motors 22 a, 22 b, 22 c, 22 d to so that any torque transferred through one of the drive shafts 64 will not result in rotation of the hub 46.

As can be appreciated, the instrument drive unit 20 described above improves usability of the surgical robotic system 1, reduces a foot-print of the overall system 1, improves safety architecture, reduces the time required to remove surgical instruments in case of an emergency, and simplifies the electronics used in the instrument drive unit 20.

It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended thereto. 

1. An instrument drive unit for use in a robotic surgical system, the instrument drive unit comprising: a carriage configured to be coupled to a robotic arm; a hub rotationally coupled to the carriage and configured to be non-rotatably coupled to an electromechanical surgical instrument; a plurality of electric motors disposed within the carriage, each electric motor of the plurality of electric motors including a stator and a rotor disposed within the stator; a plurality of drive shafts rotationally supported in the hub; and a plurality of drive gears, each drive gear of the plurality of drive gears fixed to a corresponding drive shaft of the plurality of drive shafts and configured for interfacing with a corresponding driven member of the electromechanical surgical instrument, wherein each rotor is configured to rotate a corresponding drive gear of the plurality of drive gears in response to an activation of a respective electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument.
 2. The instrument drive unit according to claim 1, wherein each stator is fixed relative to the carriage, and each rotor is rotatable relative to and within a corresponding stator.
 3. The instrument drive unit according to claim 2, wherein the plurality of electrical motors are vertically stacked within the carriage.
 4. The instrument drive unit according to claim 1, further comprising a drive motor including: a stator fixed within the carriage; and a rotor disposed within the stator of the drive motor and non-rotatably coupled to the hub, wherein the rotor of the drive motor is configured to rotate the hub about a central longitudinal axis defined by the hub.
 5. The instrument drive unit according to claim 1, further comprising a sleeve rotatably coupled to a distal end portion of the carriage and non-rotatably coupled to the hub, wherein the sleeve is configured to non-rotatably receive the electromechanical surgical instrument, such that a rotation of the hub results in a rotation of the electromechanical surgical instrument.
 6. The instrument drive unit according to claim 1, further comprising a plurality of ring gears, each ring gear of the plurality of ring gears fixed to a corresponding rotor and operably coupled to a corresponding drive gear of the plurality of drive gears.
 7. The instrument drive unit according to claim 6, wherein each ring gear of the plurality of ring gears is concentrically disposed within a corresponding rotor, such that rotation of the rotor results in a rotation of the corresponding ring gear of the plurality of ring gears.
 8. The instrument drive unit according to claim 6, wherein the plurality of ring gears are vertically stacked within the hub.
 9. The instrument drive unit according to claim 6, wherein a first electric motor of the plurality of electric motors, a first ring gear of the plurality of ring gears, and a first drive gear of the plurality of drive gears are operably coupled to one another and aligned along a first horizontal plane, and wherein a second electric motor of the plurality of electric motors, a second ring gear of the plurality of ring gears, and a second drive gear of the plurality of drive gears are operably coupled to one another and aligned along a second horizontal plane, vertically displaced from the first horizontal plane.
 10. The instrument drive unit according to claim 6, wherein the plurality of ring gears are independently rotatable relative to one another.
 11. The instrument drive unit according to claim 6, wherein at least a first ring gear of the plurality of ring gears has gear teeth on an inner periphery thereof, wherein the gear teeth on the inner periphery of the first ring gear interface with a corresponding drive gear of the plurality of drive gears, and an outer periphery of the first ring gear is attached to an inner periphery of a corresponding rotor.
 12. The instrument drive unit according to claim 1, wherein the plurality of drive shafts are circumferentially spaced from one another.
 13. The instrument drive unit according to claim 1, wherein the plurality of drive gears are vertically offset from one another.
 14. The instrument drive unit according to claim 1, wherein each drive shaft of the plurality of drive shafts has a distal end portion configured for interfacing with a corresponding driven member of the electromechanical surgical instrument.
 15. An instrument drive unit for use in a robotic surgical system, the instrument drive unit comprising: a carriage configured to be coupled to a robotic arm; a plurality of electric motors supported in the carriage, each electric motor of the plurality of electric motors including a stator and a rotor disposed within the stator; and a plurality of drive shafts circumferentially spaced from one another and configured for interfacing with a corresponding driven member of an electromechanical surgical instrument, each drive shaft of the plurality of drive shafts having a drive gear fixed thereabout, each drive gear being disposed at a discrete vertical location relative to one another, wherein each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument.
 16. The instrument drive unit according to claim 15, further comprising a plurality of vertically stacked ring gears, each ring gear of the plurality of ring gears fixed to a corresponding rotor and operably coupled to a corresponding drive gear, such that each rotor is configured to rotate a corresponding drive gear in response to an activation of a respective electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument.
 17. The instrument drive unit according to claim 16, wherein a first electric motor of the plurality of electric motors, a first ring gear of the plurality of ring gears, and a first drive gear attached to a first drive shaft of the plurality of drive shafts are operably coupled to one another and aligned along a first horizontal plane, and wherein a second electric motor of the plurality of electric motors, a second ring gear of the plurality of ring gears, and a second drive gear attached to a second drive shaft of the plurality of drive shafts are operably coupled to one another and aligned along a second horizontal plane, vertically displaced from the first horizontal plane.
 18. The instrument drive unit according to claim 16, wherein each ring gear of the plurality of ring gears is concentrically disposed within a corresponding rotor, such that rotation of the rotor results in a rotation of the corresponding ring gear of the plurality of ring gears.
 19. The instrument drive unit according to claim 15, further comprising: a hub rotationally coupled to the carriage and configured to be non-rotatably coupled to the electromechanical surgical instrument, the plurality of drive shafts being rotationally supported in the hub; and a drive motor operably coupled to the hub and configured to rotate the hub about a central longitudinal axis defined by the hub.
 20. The instrument drive unit according to claim 19, further comprising a drive motor including: a stator fixed within the carriage; and a rotor disposed within the stator of the drive motor and non-rotatably coupled to the hub, wherein the rotor of the drive motor is configured to rotate the hub about the central longitudinal axis defined by the hub. 